An semiconductor device includes a first dielectric layer, an etch stop layer, an interconnect structure, and a second dielectric layer. The etch stop layer is over the first dielectric layer. The interconnect structure includes a conductive via in the first dielectric layer and the etch stop layer, a conductive line over the conductive via, an intermediate conductive layer over the conductive line, and a conductive pillar over the intermediate conductive layer. The interconnect structure is electrically conductive at least from a top of the conductive pillar to a bottom of the conductive via. The second dielectric layer surrounds the conductive line, the intermediate conductive layer, and the conductive pillar, wherein a bottom of the second dielectric layer is lower than a top of the conductive line, and a top of the second dielectric layer is higher than the top of the conductive line.